Birth defects are a major cause of perinatal death and years of productive life lost, but the causes of many birth defects are unknown, and even less is known about how to prevent them. Genetic factors may play a role in birth defects, but it is difficult to identify the specific genetic factors because most birth defects are thought to be due to multiple genetic factors, not just one. Therefore, to sort out the role of possible genetic risk factors, data and biological samples from very large numbers of children with birth defects must be studied. Using de-identified data from birth certificates and DNA samples collected by New York State's birth defects registry and neonatal screening program, this study will identify large numbers of children with birth defects and children without such defects. The DNA from these children will be tested to identify possible genetic risk factors. Finding genetic changes that are associated with birth defects is the first step toward determining how birth defects occur (by looking at what the genetic changes do) and then, how the birth defects may be prevented (by correcting the mistakes caused by errors in the the genetic code cause).